title: Marijuana smoking does not accelerate progression of liver disease in HIV-hepatitis C coinfection: a longitudinal cohort analysis.
abstract: BACKGROUND
  Marijuana smoking is common and believed to relieve many symptoms, but daily use has been associated with liver fibrosis in cross-sectional studies. We aimed to estimate the effect of marijuana smoking on liver disease progression in a Canadian prospective multicenter cohort of human immunodeficiency virus/hepatitis C virus (HIV/HCV) coinfected persons.
  
  
  METHODS
  Data were analyzed for 690 HCV polymerase chain reaction positive (PCR-positive) individuals without significant fibrosis or end-stage liver disease (ESLD) at baseline. Time-updated Cox Proportional Hazards models were used to assess the association between the average number of joints smoked/week and progression to significant liver fibrosis (APRI ≥ 1.5), cirrhosis (APRI ≥ 2) or ESLD.
  
  
  RESULTS
  At baseline, 53% had smoked marijuana in the past 6 months, consuming a median of 7 joints/week (IQR, 1-21); 40% smoked daily. There was no evidence that marijuana smoking accelerates progression to significant liver fibrosis (APRI ≥ 1.5) or cirrhosis (APRI ≥ 2; hazard ratio [HR]: 1.02 [0.93-1.12] and 0.99 [0.88-1.12], respectively). Each 10 additional joints/week smoked slightly increased the risk of progression to a clinical diagnosis of cirrhosis and ESLD combined (HR, 1.13 [1.01-1.28]). However, when exposure was lagged to 6-12 months before the diagnosis, marijuana was no longer associated with clinical disease progression (HR, 1.10 [0.95-1.26]).
  
  
  CONCLUSIONS
  In this prospective analysis we found no evidence for an association between marijuana smoking and significant liver fibrosis progression in HIV/HCV coinfection. A slight increase in the hazard of cirrhosis and ESLD with higher intensity of marijuana smoking was attenuated after lagging marijuana exposure, suggesting that reverse causation due to self-medication could explain previous results.
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada, H2X 2P4.
authors.forename: Laurence
authors.initials: L
authors.lastname: Brunet
authors.forename: Erica E M
authors.initials: EE
authors.lastname: Moodie
authors.forename: Kathleen
authors.initials: K
authors.lastname: Rollet
authors.forename: Curtis
authors.initials: C
authors.lastname: Cooper
authors.forename: Sharon
authors.initials: S
authors.lastname: Walmsley
authors.forename: Martin
authors.initials: M
authors.lastname: Potter
authors.forename: Marina B
authors.initials: MB
authors.lastname: Klein
mesh_terms: D000328:Adult; D002170:Canada; D015331:Cohort Studies; D060085:Coinfection / Q000473:pathology*; D005260:Female; D015658:HIV Infections / Q000150:complications*; D019698:Hepatitis C, Chronic / Q000150:complications* / Q000473:pathology*; D006801:Humans; D008103:Liver Cirrhosis / Q000473:pathology*; D008137:Longitudinal Studies; D008297:Male; D008385:Marijuana Smoking / Q000009:adverse effects*; D008875:Middle Aged
keywords: HCV; HIV; cannabis; cohort study; liver disease